Lubricating compositions



United States Patent LUBRICATING COMPOSITIONS George M. Calhoun, Berkeley, and William A. Hewett,

Oakland, Calif., assignors to Shell Oil Company, a corporation of Delaware No Drawing. Filed May 19, 1958, Ser. No. 735,960 14 Claims. (Cl. 252-47) This invention relates to lubricants, particularly those useful for lubrication under severe operating conditions, such as under extreme high speed and at high temperatures.

It is Well known that the high pressure occurring in certain types of gears and bearings may cause rupture of lubricant films with consequent damage to the machinery. It is known that various base lubricants can be improved in their protective properties for rubbing surfaces by the addition of certain substances, so-called extreme pressure agents, so that excessive wear, scufling and seizure which normally follow a break in the film lubricant are minimized or prevented.

It is known that certain compounds of metal-reactive elements, such as certain compounds of chlorine, sulfur and phosphorus, as well as certain other compounds, such as some compounds of lead, impart extreme pressure properties to various lubricants. Notable among the substances heretofore used are the lead soaps, phosphoric acid esters, free or bound sulfur and certain chlorinated organic compounds. A principal objection to many of these extreme pressure agents is their generally high reactivity with the metallic surface, causing etching, corrosion and discoloration of the metal surface. Another objection to chemically reactive extreme pressure agents is that they alter the original chemical nature of the contacting surface, which under certain conditions is undesirable. Additionally, because of the activity of agents of this type, they usually are depleted rapidly resulting in only a temporary solution to the problem of extreme pressure lubrication.

It has now been discovered that improved extreme pressure lubricants are provided by a suitable lubricating oil containing oil-soluble high molecular weight mercaptomodified polymeric compounds having essentially a long linear hydrocarbon backbone chain and attached thereto in a uniform or random fashion two kinds of essential groups, one an oil-solubilizing hydrocarbyl radical, preferably an alkyl radical having an average of between 8 and 20 carbon atoms (preferably -16) bonded directly to the hydrocarbon backbone chain or indirectly thereto through a polar group and the other, which is attached through sulfur to the hydrocarbon backbone chain, rep resented by the radical S-(CH ),,X, wherein X is a polar radical such as COOR, -OR or NR where R is hydrogen or a hydrocarbyl radical, preferably an alkyl radical of from 1 to 10 carbon atoms and n is an integer of from 1 to 4. The number of -S(CH ),,X units or groups in the final polymeric compound can vary from 10 to 1000 or more, preferably from 300 to 800, inclusive.

Oil-soluble mercapto-modified [poly(thioether)]' polymers of the above type can be prepared by reacting a mercapto compound, such as mercapto acid, ester, ether, alcohol, amine, or mixtures thereof, with an oil-soluble unsaturated essentially linear hydrocarbon polymer having a plurality of oil-solubilizing alkyl radicals of from 8 to 20 carbon atoms attached directly or indirectly to a linear hydrocarbon backbone chain prepared by reacting a lower polyene hydrocarbon with a polymerizable monomer having an oil-soluble alkyl group.

The mercapto compounds include the mercapto aliphatic carboxylic acids such as mercapto acetic acid, mercapto propionic acid, mercapto =butyric, or mercapto-alkanols such as Z-mercaptoethanol, 2- and 3-mercapto- 3,041,283 Patented June 26, 1962 propanol, 2-, 3- and 4mercaptobutanol, or ethers of said mercaptoalcohols such as methyl or ethyl 2-mercaptoethanyl or mercaptoamines such as ether or mercapto esters, e.g., ethyl mercapto acetate or ethyl mercaptobutylate, ethanthiolamine, butanthiolamine and mixtures thereof.

The unsaturated polymers which are reacted with the above mercaptocompounds are long chain oil-soluble polymers prepared by polymerizing a lower (4 to 8 carbon atoms per molecule) polyene hydrocarbon with a monoolefinically polymerizable monomer having a higher hydrocarbon moiety (10- carbon atoms) such as long chain alkyl esters of alpha,beta-unsaturated acids, such as acrylic and methacrylic acids, esters of lower unsaturated alcohols, such as vinyl and allyl alcohols and long chain fatty acids, long-chain N-alkyl unsaturated fatty acid amides, such as N-alkyl acrylamides.

Suitable polyene hydrocarbons for forming the copolymers are, for example, 1,3- and 1,4-pentadiene, isoprene, 1,3 hexadiene, 1,3,5 heptatriene, 1,3 cyclopentadiene, methylcyclopentadiene, 1,3- and 1,4 cyclohexa-diene, methylcyclohexadiene, and mixtures thereof.

Representative oil-solubilizing monomer compounds which are used to form the copolymers with the polyene hydrocarbons include alpha-unsaturated long chain hydrocarbons, unsaturated esters, unsaturated amides, etc., such as decene-l, dodecene-l, tridecene-l, tetradeceriel, hexadecene-l, heptadecene-l, octadecene-l, tritriacontene- 1, tetratriacontene-l, heptacontene-l, 4-methyl-decene-1, 4,4-dimethyl-decene-l, 5,5-dimethylhexene-1, 5,5,7,7-tetramethyl-decene-l, 4,4,6,G-tetramethylheptene-1, etc., vinyl decanoate, vinyl laurate, vinyl tridecanoate, vinyl myristate, vinyl pentadecanoate, vinyl palmitate, vinyl margarate, vinyl stearate, vinyl nonadecanoate, vinyl arachidate, vinyl behenate, vinyl 4,5,6-trimethyldodecanoate, vinyl 6,8,9-triethyl tridecanoate, vinyl 12-hydroxystearate, vinyl 9,10-dihydroxystearate, vinyl chlorostearate, vinyl cyanostearate,. vinyl acetylstearate, vinyl dodecyl ether, vinyl tridecyl ether, vinyl tetracosyl ether, vinyl hexacosyl ether, allyl stearate, allyl dodecyl ether, N-lauryl methacrylamide, N-stearyl methacrylamide, and N,N- distearyl methacrylarnide.

The mol ratio of the polyene hydrocarbons to the oilsolubilizing monomer compounds can be varied within relatively wide limits, e.g., from 1/ 10 to 10/1, preferably from 1/5 to 5/1, respectively. The polymer (prior to treatment with mercapto compound) should have a substantial amount of unsaturation and have a molecular weight of at least 500 and may be up to or over 2 million, but preferably from about 2,000 to about 800,000 and still more preferred molecular weight range is from 100,000 to 600,000.

Depending on the monomers used the polymers can be prepared thermally or in the presence of a suitable catalyst. Thus, with monomers such as butadienes or isoprene and long chain alpha-olefins such as alpha-docene or alpha-octadecene, the so-called Ziegler catalysts are preferred, such as combinations of aluminum trialkyls and a variable valence metal compound, e.g., titanium tetrachloride. In the formationpf other types of oil-soluble polymers, such as copolymers of the polyene (e.g., butadiene or isoprene) with lauryl methacrylate or with vinyl stearate or with N-lauryl methacrylamide, oxygen-yielding catalysts are preferred such as, for example, various organic peroxides, including aliphatic, aromatic, heterocyclic and acyl peroxides, such as diethyl peroxide, tertiary butyl hydroperoxide, dibenzoyl peroxide, dimethylthienyl peroxide, dicyclohexyl peroxide, dilauroyl peroxide and urea peroxide. These are mentioned by way of nonlimiting examples of suitable organic peroxides. Other catalysts include sodium bisulfite, diethyl sulfoxide, ammonium persulfate, alkali metal perborates, azo compounds, such as alpha, alpha-azodiisobutyronitrile; etc.

The following Examples I-X are given as representative preparations of the intermediate copolymers for reaction with mercapto compounds to form the desired poly(thioether).

EXAMPLE I About 0.66 mole of l-octadecene, 1.33 moles of ldodecene and 0.5 mole of isoprene in cyclohexane were reacted in the presence of a Ziegler catalyst at room temperature for about 24 hours. The catalyst was destroyed by addition of methanol and polymer thereafter purified by benzene washing and precipitating from alcohol and vacuum drying. The polymer had an average molecular weight of 300,000 and an average of 750 double bonds per polymer molecule as shown by bromine number.

' EXAMPLE II About 0.5 mole of isoprene, 0.17 mole of 1octadecene and 0.34 mole of l-dodecene in benzene were reacted in the presence of the Ziegler catalyst and under the conditions of Example I. The polymer formed had a molecular weight between 350,000-400,000 and a bromine number of 120.

' EXAMPLE H'I About 2 moles of butadiene and 1 mole of lauryl methacrylate and 1% ditertbutyl peroxide were reacted at 75-100 C. for about 24 hours. The polymer was purified by'alcohol washing, filtered and dried. The resulting copolymer had a molecular weight of 3000- 5000 and substantial unsaturation as shown by a bromine number of 80 to 100.

The sulfur content of the resulting polymer is in the range of 1% to 30% and usually is about 6 to 12% by weight.

The following Examples A-I illustrate the preparation of poly(thioether) additives for use in oil compositions in accordance with the present invention.

EXAMPLE A The copolymer of Example I was mixed with about 20% excess of merca-ptoacetic acid and the mixture was reacted in the presence of tert-butyl hydroperoxide for 2-4 hours at about 40 C. The reaction mixture was diluted with diethyl ether, water washed, filtered and dried. The final average polymer molecule contained over 600 units of -S-CH COOH groups distributed in the molecule.

EXAMPLE B The procedure of Example A was followed using the polymer of Example 11 and Z-mercaptoethanol as the mercapto compound. The final average polymer molecule contained over 500 units of --S-CH CH 0H groups distributed in the molecule.

EXAMPLE C Emotional Group Temperature, Percent Example Polymer Introduced Catalyst C. S in Polymer S-OH:COOH benzoyl peroxide 40-45 6-7 S- 000E benzoyl peroxide -60 3-4 S-OH COOH o r 50-60 1 Following essentially the procedures of Examples I- 111, other polymers were prepared in accordance with the following tabulation:

The mercapto-modified [poly(thioether)] polymers in general are oil-soluble and can be used in amounts of from about 0.5% to about 20%, preferably from about I Example Catalyst Tempeature, Polyeue/oil-soluble menoolefins ratio M01 Bromine 7 wt. No.

IV Ziegler Oat Room temp..- butadieue (2)/octadecene-1 (1) 400, 000 90 V do -70- oyclopeutadiene (1)/isoprene (2)]octadecene-l (1). 250,000 80 V1 rsopreue (3)/lau.ryl methacrylate (1) 5,000 50 buadiene (2)/cyclopentadiene (1) vinyl stearate 5,000 40 Ditertbutyl peroxlde.. 80 pentadiene (3)]N-lauryl-methacrylamide (1)".-. 3,000 45 1X do 120 isoprene (3)]lauryl methacrylate (1) stearyl- 8,000 33 V methacrylate (l). r X do 100 isoprene (3)/al1yl stearate (1) 2, 000 45 M1. wt determined by light scattering technique described in Chem. Rev vol. 40, p. 139 (1948).

The final oil-soluble polymeric additive was prepared by reacting the unsaturated copolymers, such as those of Examples I-X, with one or more of the merca-pto compounds by suitable means, such as described in I our. Am. Chem. Soc., 79, 362 (1957) or Ir. Org. Chem., 22, 197 (1957), preferably between room temperature and about 100 C. and in the presence of a free radical catalyst such as an azo or a peroxide catalyst or ultraviolet light and in a non-reactive solvent such as benzene, toluene, xylene or the like. Suitable initiators include peroxides such as tert-butyl peroxide and azo compounds such as alpha,alpha-azodiisobutyronitrile or emulsion redox systems such as a mixture of sodium bisulfite and persul-fate, ammonium persulfate, alkali metal (Na) perborates, etc. s

1% to about 5% by weight. However, under certain storage and use conditions, it is desirable to incorporate into oil compositions containing these polymers a small amount (01-10%) of an oil-soluble branched-chain aliphatic monohydric alcohol. These alcohols can efiectrvely stabilize such compositions without destroying the extreme pressure properties of such oil compositions.

The oil-soluble alkanols particularly useful for this purpose are the so-called OX0 alcohols derived from branched-chain olefins, such as polymers of lower alkenes of 3 to 5 carbon atoms, and copolymers of mixtures of such alkenes, by catalyzed reaction with carbon monoxide and hydrogen in accordance with the conditions of the .OXO process, as is well known in the art.' The composition of a typical iC -oXO-alcohol' mixture derived from a mixture of C -olefins, produced by polymerization of a typical refinery cracked gas fraction of C -C hydrocarbons is given below:

Other examples of suitable alkanols include 6-methyl-lheptanol, Z-n-propyl-l-pentanol, 3-n-propyl-1 hexanol, 2,2-dimethyl-1-octanol, 10,10-dimethyl-1undecanol, 3- isopropyl-l-heptanol and mixtures thereof.

The lubricating oil base is suitably selected from various synthetic oils or natural hydrocarbon oils having a viscosity range of from 50 SUS at 100 F. to 250 SUS at 210 F. (SAE viscosity number ranging from SAE 5 to SAE 90). The natural hydrocarbon oils are obtainable from paraifinic, naphthenic, asphaltic or mixed base crudes, and/or mixtures thereof. Useful synthetic oils include polymerized oletins, alkylated aromatics, isomerized waxes, copolymers of alkylene glycols and alkyleneoxide (Ucon fluid, US. 2,425,755, 2,425,845 and 2,774,733) organic polyesters such as esters of an aliphatic dibasic acid and a monohydric alcohol, such as di- 2-ethyl hexyl sebacate or di-2-ethyl hexyl adipate esters of polyhydric alcohols and monocarboxylic acids, such as pentaerythritol tetracaproate, and the like. Useful Ucon fluids are Ucon 50HB170, Ucon 50HB660 or Ucon LBSSOX, which are copolymers of ethylene and 1,2- propylene oxides; the diols as well as their monoand dialkyl ethers are useful. The hydrocarbon oils may be blended with fixed oils such as castor oil, lard oil and the like and/or synthetic oils as mentioned or silicone polymers and the like. Typical oils of this type are petroleum motor oils (A) and (B), characterized below,

(A) being paraflinic in character and (B) naphthenic in character:

Petroleum Oil (A) (B) (SAE 10W) (SAE 30) Pour point, F 10 5 390 415 Viscosity, SUS at 210 F 44 50 Viscosity Index .s 90 65 Other suitable oils are specification gas turbine lube oils having the following properties:

Grade 1010 1065 Flash, COO, F 300 465 Pour, F 10 0 Viscosity, SUS at 100 59. 4 530 Neutral Number 0.02 0.01 Ash None None The following compositions are illustrative of the invention, the percentages being by weight:

Composition A Example A additive 2%.

Composition D Example A additive 2%. C H OH(OXO- alcohol) 6%. 1010 Mineral oil Balance.

Composition E Example D additive 1%. 1010 Mineral oil Balance.

Composition F Example B additive 2%. C13H2'7OH(OXO alcohol) 4%. a 1010 Mineral oil Balance.

Composition G Example E additive 3%. SAE Mineral oil Balance. Composition H Example F additive 2%.

C H OH(OXO alcohol) 6%.

SAE 90 Mineral oil Balance.

' 1 Composition I Example A additive 5%.

Ucon 5'0HB660 (polyethylene-propylene glycol having a SUS viscosity at F.

of 660) Balance.

Composition J Example A additive 5%. Di-Z-ethylhexyl sebacate Balance. Compositions of this invention were evaluated for their extreme pressure properties on a Spur-Gear machine. The machine consists essentially of two geometrically similar pairs of gears connected by twoparallel shafts. The gear pairs are placed in separate gear boxes, which also contain the supporting ball bearings. One of the shafts consists of two sections connected by a coupling. Loading is accomplished by locking one side of the coupling and applying torque to the other. The conditions of the test were:

Speed3200 Oil temperature100 F.

Oil fioW-rate-IO cc. sec.

Load in increments 5 min, at each setting Compositions A, B, D and F carried score loads of from 3,000 to 12,000 lbs./in., Compositions I and J are equally eifective and Compositions C, E, G and H carried score loads of over 1,500 lbs'./in., on the other hand, 1010 mineral oil containing separately 2% of the polymers of Ex I to X carried score loads of about 700 draulic fluids of the oil, water-in-oil emulsion or synthetic .type with respect to wear inhibition and the like.

We claim as our invention:

1. A lubricating oil composition comprising a major amount of mineral lubricating oil and from about 0.5% to about 20%, of an oil-soluble high molecular weight polymer containing C C alkyl groups and S-(CH X groups attached to different carbon atoms of a linear hydrocarbon chain wherein n is an integer of l to 4 and X is a polar group selected from the group consisting of COOR, selected from the group consisting of hydrogen and C alkyl radicals said polymer having a sulfur content OR and NR and R is] of from 1% to 30%, and a molecular weight from 2,000 7 2. A lubricting oil composition comprising a major amount of mineral lubricating oil and from about 0.5% to about 20%, of an oil-soluble linear hydrocarbon polymer containing C -C alkyl groups and groups attached to different carbon atoms of the linear amount of mineral lubricating oil and from about 0.5%

to about 20%, of an oil-soluble linear hydrocarbon polymer containing -C -C alkyl groups and groups attached to difierent carbon atoms of the linear hydrocarbon chain, said polymer having a sulfur content of from 1% to 30% and a molecular weight of from 2,000 to 800,000.

5. A lubricating oil composition comprising a major amount of mineral lubricating oil and from about 0.5

to about 20%, of an oil-soluble linear hydrocarbon -C -C alkyl groups and -SCH CH NH groups attached to different carbon atoms of the linear hydrocarbon chain, said polymer having a sulfur content of from 1% to 30% and a molecular weight of from 2,000 to 800,000., v 1

6. The composition of claim 3 wherein the C -C alkyl groups are attached to the linear hydrocarbon chain through carboxyl groups,

polymer containing I through amide groups.

7. The composition of claim 4 wherein the --C C alkyl groups are attached to different carbon atoms in the linear hydrocarbon chain through carboxyl, groups.

' 8. The composition of claim 3 wherein the C -C alkyl groups are attached to the linear hydrocarbon chain 9. A lubricating oil composition comprising a major amount of mineral lubricating oil and from about 1% to about 5% of an oil-soluble linear hydrocarbon polymer containing C C alkyl groups and -SCH CH OH groups attached to different carbon atoms of the linear hydrocarbon chain, said polymer having a sulfur content of from 6% to 12% and a molecular weight of from 100,000 to 600,000.

10. The composition of claim 1 containing from 0.1% to 10% of an oil-soluble branched-chain alkanol containing 8 to 13 carbon atoms.

11. The composition of claim 3 containing from 0.1% to 10% of an oil-soluble branched-chain alkanol containing 8 to 13 carbon atoms.

12. The composition of claim 4 containing from 0.1%

' to 10% of an oil-soluble branched-chain alkanol containing 8 to 13 carbon atoms.

13. The composition of claim 5 containing from 0.1% to 10% of an oil-soluble branched-chain alkanol containing 8 to 13. carbon atoms. g '14. The composition of claim 6 containing from 0.1% to 10% of an oil-soluble branched-chain alkanol containing 8 to 13 carbon atoms;

References Cited in the file of this patent 7 V UNITED STATES PATENTS 2,581,092 Garber et a1. Jan. 1, 1952 2,800,450 Bondi et al.' July 23, 1957 2,892,783 Stu-art et al. June so, 1959 FOREIGN PATENTS 761,897 Great Britain Nov. 21, 1956 776,455 Great Britain .a June 5, 1957 OTHER REFERENCES 

1. A LUBRICATING OIL COMPOSITION COMPRISING A MAJOR AMOUNT OF MINERAL LUBRICATING OIL AND FROM ABOUT 0.5% TO ABOUT 20%, OF AN OIL-SOLUBLE HIGH MOLECULAR WEIGHT POLYMER CONTAINING -C8-C20 ALKYL GROUPS AND -S-(CH2)NX GROUPS ATTACHED TO DIFFERENT CARBON ATOMS OF A LINEAR HYDROCARBON CHAIN WHEREIN N IS AN INTEGER OF 1 TO 4 AND X IS A POLAR GROUP SELECTED FROM THE GROUP CONSISTING OF -COOR, -OR AND -NR2, AND R IS SELECTED FROM THE GROUP CONSISTING OF HYDROGEN AND C1-10 ALKYL RADICALS SAID POLYMER HAVING A SULFUR CONTENT OF FROM 1% TO 30%, AND A MOLECULAR WEIGHT FROM 2,000 TO 800,000. 